﻿#include<iostream>
using namespace std;
int main() {
	if (int a, b, c; true) {//C++17新特性，能把新建变量写入判断位置上
		a = 2;
		b = 3;
		c = 5;
	}
	else {
		a = 1;
		b = 2;
		c = 3;
	}
}

//switch和if都要加括号，不然变量下一条也能用